Cloyster is a Water and Ice-type Pokémon in Pokémon Go, and it has several weaknesses that can be exploited by other types of Pokémon. Here are some of the best counters for Cloyster:

• Electric-type Pokémon: Electric-type moves are super effective against Cloyster, making Electric-type Pokémon like Mega Diancie, Shadow Raikou, and Mega Ampharos great choices for battling Cloyster.

• Fighting-type Pokémon: Fighting-type moves are also super effective against Cloyster, so Pokémon like Mega Blaziken, Terrakion, and Machamp can deal significant damage.

• Grass-type Pokémon: Grass-type moves are super effective against Cloyster, so Pokémon like Venusaur and Mega Sceptile can be effective.

• Rock-type Pokémon: Rock-type moves are super effective against Cloyster, so Pokémon like Rampardos and Tyranitar can be good choices.

Its important to note that Cloyster is resistant to Ice and Water-type moves, so its best to avoid using Pokémon that rely on those move types. Additionally, Cloyster can be soloed by high-level trainers, but lower-level trainers or those without ideal counters may want to bring a friend.